What proved to be crucial for the Gujarat police, which on Saturday claimed to have busted a pan-India network behind the serial blasts in Ahmedabad [Images] and other cities in the country, were five mobile phones.

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"We had received leads into the case on the basis of five mobile phones used by the conspirators of the blasts," Joint Commissioner (Crime Branch) Ashish Bhatia told media persons as police claimed to have solved the July 26 serial blasts by arresting 10 alleged SIMI [Images] activists, including mastermind Mufti Abu Bashir.

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Explaining the modus operandi followed by police to crack the case, he said, "During our investigations, we found five mobile phones with SIM cards that enabled only incoming calls were being used prior to the blasts."

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Bhatia said police noticed that all incoming calls were made PCOs.

"Interestingly, the phone became inactive in the evening of July 26, the day the blasts took place," he said.

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Police claimed that it was this clue that led them to Bashir, who was arrested on Saturday in a joint operation of police teams from Gujarat and Uttar Pradesh [Images].